Odds and Ends

Component Tray

Menu and contextmenu

Splash Screen

Examples in this show

• Mainmenu

• Context menu

• Errorprovider

• Splashscreen

• Cellular automata

The component tray contains:

• Timer

• Errorhandlers

• Print capabilities

• DialogBoxes

• Menus

• Context menus

Adding a main menu

• Most apps nowadays have menus – MS powerpoint and the VB IDE both do.

Add Mainmenu to component tray from toolbox

Selecting the mainmenu control allows you to begin editing the menu

and editing…and editing

add submenus to a menu item by filling in the little box that appears below or next to it.

As with other controls, it is a good idea to rename menu items from MenuItem1,…to

mnuFile, …

shortcut keys

• You can add shortcut keys to a menu item by selecting shortcut in the properties for this item. Select the shortcut you wish to associate with the menu item.

Ctrl-s for save

More about menus

• Menu items display their submenus automatically if they have them.

• You add itemclick subs to add functionality to menu items that have no submenu.

Save clicked event handler

• Private Sub mnufilesave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles mnufilesave.Click

• MessageBox.Show("save selected", "Menu", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

• End Sub

Clicking save in debug

Context menu

• A context menu is added (to the form component tray) from the toolbox.

• When you right-click a control information can be displayed.

Context menu

Add context menu to a control in properties

Add to context menu as you would to a regular menu

Add sub code to context

Context menu popup code

Private Sub ContextMenu1_Popup(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ContextMenu1.Popup

MessageBox.Show("context", "context", MessageBoxButtons.OK, MessageBoxIcon.Asterisk)

End Sub

Menu example exe

• In p:\vs\menu

Handling errors

• Handling errors with an errorprovider

• It is added to the component tray

Handling errors

Error provider

• An errorprovider is added to the component tray

• In this project the “causes validation” property of the two textboxes are both set to true

• Just the validation code was written – no other processing

Build error provider when form is loaded

Private Sub frmmain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

errorhandler = New ErrorProvider()

End Sub

Corrected one error, now have another

Another ss entry error

Finally: Corrected ss num error

Two event handlers provided – the validation for the textboxes

Private Sub txtint_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtint.Validating

Dim int As Integer errorhandler.SetError(txtint, "")’ clear any old errors Try int = Integer.Parse(txtint.Text)

Catch ex As Exception errorhandler.SetError(txtint, "field must be int") e.Cancel = True ‘cancel event End Try End Sub

Part of ss validationPrivate Sub txtss_Validating(ByVal sender As System.Object, ByVal e As

System.ComponentModel.CancelEventArgs) Handles txtss.Validating ' Me.Refresh() errorhandler.SetError(txtss, "") Dim ss As String ss = txtss.Text If ss = "" Then errorhandler.SetError(txtss, "field required")

e.Cancel = True ElseIf ss.Length <> 11 Then e.Cancel = True errorhandler.SetError(txtss, "field must contain 11 chars")

ElseIf ss.Substring(3, 1) <> "-" Or ss.Substring(6, 1) <> "-" Then‘’’’’there’s more

End IfEnd sub

Errorprovider example

• In p:\vsp\errorprovider\bin\...

• There is more to do with this example… like enable navigation and exit without correcting the error.

Splash screen: comes up briefly with some info when a form is loaded

Splash screens:

• Create a main form with just a label and exit button

• Add the exit code (me.close())

• Add a second form to the project called frmSplash

Splash screens:

• On frmsplash put:• Information about the

application, copyright, programmer, date, pictures, whatever.

Splash screens:

• Add a timer with interval 5000 to the frmspash. In the timertick sub put– Me.Close() ‘close form after 5 sec

• Be sure to start the timer in the frmsplash load sub.

Splash screens: set topmost property to true

set frmsplash formborderstyle to fixedtool (so it can’t be resized)

Back in frmmain

• Add formload code to create an instance of the frmsplash. Recall this code is:

Dim x as frmsplash

x.show()

• When frmsplash loads it will start its timer.

• Exe in p:\vs\splash\splash.exe

Cellular automata: in p drive vb folder

Cellular automata

• There are many examples of uses of cellular automata, from biological modeling to designing fabric patterns.

• I cover only a little bit about them here.

• Discussion of 2-d automata

• Discussion of 1-d automata

One dimensional automata

• The original values are stored in an array. These might be generated randomly, or come from measurements.

• Display (in VB) might be in a panel.• The “first generation” consists of a single set of

rectangular colors. Each color represents an integer in the array.

• The next generation is computed from the first (usually) according to some formula for example:

• Newvalue(i)=(old(i-1)+old(i)+old(i+1)) mod maxcolors• You’ll need two one dimensional arrays, and you’ll have

to keep copying the new values back into the old array, and displaying.

Two dimensional automata

• Two d automata are displayed similarly to one-dimensional ones: each value represents a color.

• But each new generation is computed in two dimensions, often using some rule about how many neighbors a given cell has in the current generation.

Two dimensional automata

• A sketch of the code goes like this:

1. Assign initial values to a fairly large (like 100X100) array.

2. Loop a bunch of times or do on buttonclick:

3. Compute next generation values into a new array

4. Display the current generation

5. Copy next generation into current

6. endloop

Example..in p:\vb\twodcellularautomata.exe